Roof construction in a built-up flat or low-pitched roof generally consists of a roof deck, an insulation barrier above the deck, a weather resistant layer applied to the insulation layer, and optionally a layer of heat resistant material. The roof deck generally includes materials such as wood, gypsum, concrete, steel, and the like. The roof deck can refer to the existing roof, including the existing insulation and weather resistant layer. Above the roof deck, insulation boards are typically applied to provide thermal insulation and a uniform surface to which the weather protective layer is applied. The most common insulation boards are made of polyisocyanurate boards faced with cellulosic facers reinforced with fiberglass. The facers are typically bonded to both major surface areas of the board. Other facers which may be employed include those that are either rigid or flexible and are optionally fire or flame-retardant. Insulation boards can be used in new roof applications as well as reroofing operations.
Recovery boards, as they are referred to in reroofing, have been employed where the existing roof is leaking. These boards are generally applied to a built-up roof deck to provide a uniform surface when recovering an existing roof. To seal the roof from the elements, the insulation or recovery boards are typically covered with various materials including molten asphalt, modified bitumen membrane, rubberized asphalt, or an elastomeric composition such as EPDM (ethylenepropylene diene monomer). The heat resistant layer of material, which is generally applied directly to the weather resistant layer, can include gravel, river stone, foam or a layer of mastic followed by granules.
Application of the weather protective layer can be accomplished by a number of means, usually dictated by the type of material employed. For example, sheets of a protective membrane can be rolled out over the roof and bonded together by torching or the use of an adhesive.
The patent literature does include panels and boards used for roofing operations. Built-up roof constructions and the components thereof, for example, are well-known in the art as generally explained in Forte et al, U.S. Pat. No. 5,129,598, Blanpied, U.S. Pat. No. 5,001,005, Dybsky et al., U.S. Pat. No. 4,944,818, and Rosato et al., U.S. Pat. No. 4,388,366. With regard to insulation boards, Forte et al is directed toward composite sheathing boards which provide effective thermal insulation while remaining permeable to the transmission of water vapor. The boards comprise a polymer foam core, including polyisocyanurate, polyurethane, polystyrene and the like, and optionally at least one facer. While the patent discloses that facers may not be required, if the manufacturing process does not demand their use, they are nevertheless preferred.
Blanpied teaches a rigid foam board comprising a thermosetting plastic foam sandwiched between two facers; the facer comprising glass fibers, non-glass filler, and non-asphaltic binder. Likewise, Dybsky et al. teaches a composite roofing substrate panel comprising a core of combustible material such as fibers or foams and a facer of noncombustible material such as glass fibers coated with a bituminous material. Rosato et al. teaches a laminate insulation board comprising a plastic foam core and at least one facer sheet forming both a protective layer and a venting means for fluids; the facer sheet comprising fine glass fibers bonded together with polyvinyl acetate.
Although the above described insulation boards teach the use of at least one facer, the addition of facers to polyisocyanurate foam boards adds cost. Furthermore, the facers heretofore employed are typically not water resistant. Thus, the elimination of the facers would both lower production costs and improve the moisture resistance of the boards.
In some applications, such as when ballasted EPDM is employed, facers may not be required. Nonetheless, present manufacturing practice requires a barrier between the laminator slats and the foam to prevent the foam from sticking to the slats. Furthermore, even if boards could be produced in the laminator without employing facers, a further problem that would be encountered is that the bundles would stick together, especially as the internal temperature of the bundles increases. Thus, facers are further required to separate the boards during storage and transportation.
Accordingly, a need exists for an insulation board which can be manufactured without facers. Moreover, such boards must be dimensionally stable and not warp or bow when wet.